Security products should make our computers more secure, not less. Little Snitch is the de facto personal firewall for OS X that aims to secure a Mac by blocking unauthorized network traffic. Unfortunately bypassing this firewall's network monitoring mechanisms is trivial...and worse yet, the firewall's kernel core was found to contain an exploitable ring-0 heap-overflow. #fail Though briefly touching on generic firewall bypass techniques, this talk will largely focus on the kernel-mode vulnerability. Specifically, I’ll discuss bypassing OS X specific anti-debugging mechanisms employed by the product, reverse-engineering the firewall's I/O Kit kernel interfaces and 'authentication' mechanisms, and the discovery of the exploitable heap-overflow. Finally, methods of exploitation will be briefly discussed, including how an Apple kernel-fix made this previously un-exploitable bug, exploitable on OS X 10.11 So if you simply want to see yet another 'security' product fall, or more generically, learn methods of OS X kernel extension reversing in a practical manner, then this talk is for you :) Bio: Patrick Wardle is the Director of Research at Synack, where he leads cyber R&D efforts. Having worked at NASA, the NSA, and Vulnerability Research Labs (VRL), he is intimately familiar with aliens, spies, and talking nerdy. Currently, Patrick’s focus is on automated vulnerability discovery, and the emerging threats of OS X and mobile malware. In his personal time, Patrick collects OS X malware and writes free OS X security tools. Both can be found on his website; www.Objective-See.com